Process and apparatus for refining mineral oils



W. G. LAIRDy Dec. 26, 1933.

PROCESS AND APPARATUS FOR REFINING MINERAL OILS Filed April 4, 1927MQQQQ Patented Dec. 26, 1933v -1- ,UNITED PTNT This Y rRooEssAND'Arrnaaros Fon REFINING `v`ivnNEaAit oILsn w Y VWilbur efraim. New York,N. Y., assigner to' Heat Treating Qonrpany, NewYork, corporationjofDelaware Appucatan'iiapfil 4, 1927.

' 'ji 1o claims.' ',(ol. 19e-69) invention` relates to a processandjappa ratus ffor refining mineral oils. "more particularly to the artof converting crude or other mineral y oil products into gasoline likematerial.'

The present invention isA Van improvement on the well known tube anddrum oil cracking systems in Which oil to be cracked is 'passed underheated coil `mounted in affurnacatheninto a large .drum or still wherevthe oil remains for a considerable time in order to allow the crackingreaction to complete itself.

`Probably the most outstanding disadvantage met with in the use of suchcracking *systems is the accumulation o f `carbon in the'drum and ofteninthe dephlegmator which is used to `ex-V tract theheavier products froming the accumu I the vapors leav reaction chamber. This carbon orcokelation must beremoved at very frequent intervals, which necessitatesftheshut down of the app aratus with subsequent cooling before the Workmencan removethe hardened `carbon from the .drum With pick and shovel orbefore boring or other devices can be used to remove the same.

In the use of the usual systems andoperating methods the principallossire'sulting from` the accumu lation of carbon is the time lost incoolving the apparatus so thatthe carbon can be removed and that`lostoin starting up the appa'.-

fio

ratus again. Time consumed V in these operations l cuts down theproductionof the apparatus, While the operating cost increases. If it isassumed'for example that the cracking apparatus Vmust be shutdown forseveral days each month toremove carbon vthe .decrease inproduction willbe from l0 tof25%,whicl1 if avoided would result inA a `substan costs cotially equal prent; because the operating ntinue just the same. Y v-Anotherv defect vin present apparatuses and mode of operating the sameis that where carbon is continuously allowed to :accumulate in thecracking drum the available storage for' hot oil becomes less andiess sothat they time allowed for the cracking reaction becomes shorter'as-the. run continues. I f

In present systems also the cracking operation is allowed to extend into.the dephlegmator'which is commonly used to receive Vanors'frorn` thecracking orgreaction drum. Thisris particularly true after acertainamount of carbon; pitch and tar is allowed' to collect in the 4reactiondrum. Cracking inthe dephl'egrnator naturally produces carbon.

etc., which-cakes on the metalsurfaces or is returned' to the-heatingfurnace with the reiiux c ondensatze and thereby promotes the acandwhich may be a mineral oil of any type such as an asphaltic or parainoils, ris introduced into rkto point out that the oil in the heatexchangers 4 N.v y., a

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cumulation of carbon and coke in the furnace tubes". l j Wherefore thepresent invention hasl for its object: .f

The Aprovision of a process and apparatus wherein theVariousdisadvantages enumerated aboveare overcome: 1 -f v The provisionof an apparatus adapted to carry out the novelprocess pointed outhereinafter;

The provision of an apparatus'adapted to opero ate continuously at high.temperatures and pres-v sures: n "The provision of an oil .crackingapparatus adapted to provide a constantstorage-capacity for the oilundergoing cracking; To provide a continuous process for the crack,-ingof mineral oils as distinguished from processes in which kit isnecessary to shut down to remove carbon; f f N v H v`Tofprovide acracking process in which a constant volume of oil may vbemaintainedinthe cracking zone; and. f f y lTo provide a process-forcrackingmineral oils in which the cracking ofthe oil isv restricted tothe reactionfzone and not'allowed togo on in l the dephlegmator.

These and other objects will be apparentzfrom the following detaileddescription taken in'. connection with the accompanying drawing* inWhicru-L- Y. y g f 85 The figure is a diagrammatic elevational viewpartly in section of an apparatus-in'y accordance' with the inventionVandin whichV the Inovel `process may be carriedout. l i 'f VVReferringto the drawing the oil to .be cracked base crudejoil, distillate l orresiduumgfshale oil, oils resulting` from the distillation of coal yor amixture of any of these the apparatus vthrough v95 the'pipe 2 by anyconvenient means such asa pumpV (not'f shown). Thef'oil thus`vintroduced passes' downward through a series of heat interchangers 4,mounted on a dephlegmating and The detailsof construcdescribed in aYpending application Serial No.. 125,893,y filed July'BQ, 1925'. Forpresent/'purposes .it Will be suicient 105 passes in heat exchange butout of contact with vapors from a cracking chamber described later.-

vThe pipe 8` discharges 'into va tank `10 from which theV preheated oilpasseslby a valved pipe v12 to a tubular'cracking furnacef14. `where theoil 110 is heated to or above the cracking temperature under pressure.This furnace heater may be of any of the conventional pipe still furnacetypes.

VThe highly heatedv oil leaves the heater 14 by a In order to makeproper connections with inlet and outlet pipes the ends of the chamber18 are provided with central stu'ng boxes 24. At the inlet end the pipe16 connects through a T with a perforated distributor pipe 26 whichextends through the stuffing box 24 and into the chamber 18 aconsiderable distance. At the oppositeend of the chamber a vapor outletpipe 28, arranged as shown, to extendabove the liquid level in thechamber 18, passes through the stuiling box 24 at the outlet end of thechamber. Within the chamber is placed a number of metal balls 30, which,as thechamber rotates, Akeep the carbon formed and deposited in thecracking operation from accumulating on the walls.

From the rotatable reaction chamber 18 the vapors pass by the offtake 28which is connected to a valved vapor pipe 32 discharging into a chamber34 forming the base of the tower 6. This chamber may or may not beconstructed integral'with the dephlegmating tower, but for convenienceis shown so constructed. The vapors entering the compartment orchamber`34 are sists of an .open ended pipe Vextending through and abovea partition plate 42 which forms the upper vpart of compartment 34.These vapors thenpass through a series of alternately placed bubble captrays 44 and heatinterchangers 4, so

'thatthey alternately pass through condensate maintained-on the traysand in heat exchange with charging stock passing through the exchangers4. During the passage of the vapors through these various condensing andrectifying stages intheftower 6 the condensate produced in the units 4flows 'counter to the vapors back onto'the bubble cap tray next below,while the condensate on the trays passes by conventional 'overflowpipes'onto the next bubble tray below and from'the lowermost tray intothe condensate trap'formed bythe pipe 40 on the partition 42 Betweeneach bubble tray in the tower is placed ay dead plate 46 which causesvapors to pass through suitableopenings (not shown) into the heatexchangers 4, from which the vapors not condensed pass 'by otheropenings into the space below the bubble tray next above.

While the condensate collecting on the partition 42 has a temperatureconsiderably above that of the end point of gasoline it neverthelesscontains absorbed gasoline (2 to 4%) which may be stripped therefrom bybubbling a gas through the condensate. This is accomplished by means ofa gas distributor 48 mounted above the partition 42, gas being suppliedhot or cold as desired from any suitable source by the valved pipe 50.Stripped condensate is withdrawn by a pump 52 through a pipe 54 andintroduced into the advancing charging stock in one of the exchangers 4by a pipe 56. The invention is not limited to the particular point atwhich the reux condensate is mixed with Vthe charging stock, since suchmixing may be made in any of the exchangers 4, the tanklO or line 12 asdesired.` It is preferred to maintain a considerable'body of condensateon the partition 42 in order to secure effective stripping of thegasoline therefrom. This may advantageously be accomplished bycontrolling the speed and operation (starting and stopping) of the Vpump52' by an automatic device controlled in turn by the level of theliquidV condensate in the chamber abovethe plate 42. n

The vapors and gases remaining uncondensed in the tower 6 are conductedby a valved pipe 58 to a condenser 60 which may be cooled by ico wateror by cold charging stock before it enters the exchangers on the tower6. The condensate thus produced together with fixed or non-condensedgases pass by a valved pipe 62 to a trap 64 fromwhich the condensedproduct isV drawn by a valved pipe 66 and the gases by a pipe 68. Thefixed gases may be scrubbed and sent to storage by a valved pipe '70 ora portion of lthem (scrubbed or not) may bemixed with the charging stockby means of a booster '72 and pipe 74 which connects with the chargingline 2. Y

In the operation of the apparatus a body of oil is accumulated andmaintained in the reaction drum 18 to a vlevel slightly above the axisso vthat the oil and vapors from the pipe still 14 are disiis tributedinto such. body by the distributor pipe 26. This body of oil, from theVery nature of the process. consists of aA mixtureof hydrocarbons(including absorbed gasoline), polymers, etc.. tar, pitch, Vcoke andcarbon. Because of the tendency of the tars and carbon to settle out ofthe mixture (even when the chamber 18 is rotated) provision is made fortaking olf the cleaner material by a'valved draw ofl pipe '76 whichpasses centrally through the vapor oiftake 28 and discharges directlyinto the compartment 34. The heavier material including the carbonand'pitch in suspension is withdrawn by asimilar valved pipe 78centrally placed in the opposite end of the' chamber 18, this pipehowever being bent downward inside the chamber so as to draw oil fromthe bottom thereof.. Oil and carbon withdrawn by the pipe '78 areYdischarged into a stripper or concentrating stillj80 where the lighterproducts are distilled therefrom by introducing a gas through a gasdistributor 82 mounted in the bottom of this still. The distillation iscarried out at the same pressure as that used in the cracking still 18so that the vapors evolved may be delivered either by a valved pipe 84(by means of an aspirator) into the transfer line 16 or by a valved pipe86 into the vapor line 32.

Which pipe to use will largely depend on the temperature of the vaporsleavingthe stripper 80 and/or the viscosity of the oil in the chamber 18which should be maintained belowl the saturation point of the tarrymatter therein. The

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- to the Aextent distillation in thejstill L'is preferably carried ofleaving only 4oil 4of the fuel oil type' together "with r'thesuspendedvcarbom tar, pitch, etc., this mixture being withdrawn throughal valve pipe 88 Vinto avcooler 90 from which the cooled mixture ispassed to a'thickener A92 kby a pipe '94. `The oil-carbon mixture entersatthe top andnear `the center of thethickener, which by proper operationproduces la'rapid separation ofthe oil from the carbon,t heoiloverflowing into a troughiQG Yfrom which it is drainedby'a valved pipe98,while the carbonis discharged at the bottom through a pipe bythe aidof-'a steam Aorgas ljet from 1a pipe10`2'.` The oil delivered lby the`pipe 98,r may be reintroduced into Vthe feed line at any point'or maybe'used in the chamber 18 to carry out more carbon, etc., but it isusually too heavy for these purposes and is preferably used as fuel oil.

The relatively clean oil delivered to the chamber 34 from the crackingvessel 18 mingles with the oil sprayedhfrom the distributork3`6 and thecondensate produced thereby. This Ymixturecontains an appreciable amountof absorbed gasoto draw oil from Athe chamber 10. Gas from the booster'72 may alsobe used in the injector 111 'for forcing the oil through theheater. It is preferred to maintain a substantial body of oil labove thedistributor in chamber 34, which may be done automatically in the mannerreferred to above in connection with the oil level'maintainedrabove thepartition 42; n

'I he useoi` a gas, particularly the non-condensed gasjfrom the nalcondenser, with the feed oil is especially desirable whensuch-stock asgas oil is used for cracking, due Vto the fact that a lower vaporizingtemperature is secured inthe heat interchangers 4 where heat ofycondensation of vapors `from the still may be directly transferred toheat of vaporization lof the charging oil. Where, however, itisdesirable to maintain a strictly liquid phase ofthe lcharging oil'theAgas circuit may be omitted-` A Y 'In carrying out the process theoperation is `rendered continuous by the use of the ball'mill typereactionvdrum 18V in" such a manner asto keep the carbon and coke,formed by cracking of the oil, in a fine stateof subdivision so that itmay be removed with the oil withdrawn'by pipe 78. The balls 30 whichymay be made of iron or steel should be suiciently large and heavytofunction properly in grinding up the carbon and coke produced incracking and a sufficient number should be used to give intimate rollingcontact with' each ,other andthe fulllength of the bottom of the drum.As the drum is rotated with the metal balls 30 arranged in the mannerindicated the walls of the rdrum are kept Yfree from any coke depositand therefore the full capacity of the chamber is always in use.

The rotation ofthe drum may be either continuous in one direction oroscillating'. The osn lcillating'motion may be progressive, th'atis; arotation flrst in one direction'vthrough a definite angle' then in theotherv` direction through a lesser or greater angle so that eventuallyacomlejector type so n charging stock it'may thermostat may pleterotation is made rotated )at any reasonablefspeed but u'sually'a" Veryslow rotationA is sufcient to maintain the carbon insuspension andprevent coking on the walls. Infact an intermittent rotation of lsay Thedrum may alsobeVv is rotated for one day each week the carbon ac'- 'ycumulation' can .be completely 'removed without the necessityV of vevershutting down exceptfor fother causesr such as inspection or repairs.-The `rafteof rotation vor the frequency of the periods .ofrrotation willof course vdepend to lsome extent on the temperatures and pressures usedin the lcrackingv apparatus or'. with the relative amount of unvaporizedoil in the system which lmay, Vif found --desirable be all withdrawn bypipo '78. l l

, If the'intermittent rotation of the drum 18 jis practised the Yvalvein pipe 76 may be closed duringl rotation rand that in pipe r'78 leftopen so that the carbon being removed from the balls 30 and walls of thechamber will be more rapid# Y ly washedout.y During such a period thevalve in pipe 84 may be open inv order to increase'the amount andtherefore the fluidity of the 'oil put through the drum 18. Theconnectionv between pipe Stand 16A is preferably of the aspirator or ythat the flow of the fiu'idsin pipe 16 will draw vapors from the pipe84. Such connections are common and therefore notl shown.

When continuous rotation of the reaction aus noV

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chamber is practised the intake end of the pipe 76 may be screened if itis found that -too much carbon is being withdrawn by thispipe dueto theagitation in chamber 18.:V

In order toavoid contamination and stoppage with carbon of thedephlegmating and rectifying'part of the apparatus'it is an objectofthe` present invention to .restrict the cracking operation-to the pipestillfurnace lfiandl the drum 18. 'Sincethe oil and vapors leavingAthevcracking chamber by pipes y'76 and 32 are considerably above thecracking temperature provision is made for their cooling by vtheuse of arelatively cool oil from 'the spray 3 6 and the vaporization producedyby the stripping operation'in the lower part of chamber 34., If a crudeoil is being used asa gasoline hydrocarbons by being all passed'through"the distributor 3,6v in Vwhich event the valvev in 'pipe '12 would bebe completely-topped' of 'A y 'no' e, i

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used to control the valve in pipe 38 so that the quantityof coolingrfluidwill be governed bythe outlet temperature. This will also tend tovgive a constant perfo rrnaricev,by4 the-rectifying tower andthereforemoreuniforrnproducts.

The rotary crackingrchainber 18 may beused in aconsid'er-ably differentmanner 'to that 'described above by providing two such chambers soarranged that one may be cut out ofthe systern when the other is use. Ifthis is vdone the stunng.' boxes yare preferably substituted vbylangesand no grindingelements' will be placedY in the chamberinpirci-iit. When a reactionV chamber has been in circuit rfor some timeand hasaccumulated considerable carbon it is cut out and another cut inby a proper valve system. The one out of use isunbolted from theconnecting pipes and either rotated in place or rolled on rails, whichmay take the place ofthe rollers 20, to a cleaning` system into-which itis then connected. This system will comprise. a means similar to the oneshown for rotating the drum 18 together with oil storage and a carbonlter or separator. After the druin to be cleaned of carbon is placed inthe cleaning circuit a number of balls similar to the balls 3) are runinto it and the drum rotated to pound. up and free the carbon and cokecollected therein. During rotation a stream of oil o r water is run.from a storage tank through the drum to carry out the pulverized carbonand coke which is continuously separated from the oil in any convenientinanner such as by means of a thickener. The oil is used over and overfor this purpose. The use of two cracking chambers with one always incircuit gives ample time for the one out of circuit to be cooled,cleaned and replaced while the other is collecting carbon, coke, etc.above operation it is understood that either vor both of thewithdrawallines 767er '78 may be used as long as possible to withdrawoil and/or oil with carbon in suspension. The above described method ofcleaning a reaction drum may of course be used where only one drum isavailable in the cracking unit. n

The eiiiciency of the process is greatly increased by the use of thestripping chambers orv stills 80, 34 and that above the partition 42,

` by which all gasoline hydrocarbons are removed ,per square inchisysuilicient. y -the yapparatus may be maintained under differfrom theoil either before it is reintroduced into the heating tubes ordischarged as residuum.

Furthermore sincethe charging stock is to contain no gasolinehydrocarbons or is to be freed of such, a larger percentage will becracked to gasoline in accordance withthe Vlaw of mass action. Upon vthesame principle the introduction of the non-condensed gases from thersystem into the charging oil tends to prevent the formation of suchgases during the cracking of the oil. Ii crude is vbeing topped asreferred to above,

gas from pipe '74 may be introduced directly into the line l2 beyond thevalve. For'the same reason that non-condensed gases are passed with thecharging stock they are preferably heated.

and used in the chamber if vapors therefrom are putin the line `16. l

The cracking apparatus may be maintained under anydesirable pressureconsistent with the proper safety factors for the-materials ofconstruction, but ordinarily from 150 to 300 pounds Certain parts of ent.pressures than other lparts (such as a progressive reduction) by theproper manipulation of4 the valves in pipes 16, 32, 76, 58 and 62. Thebooster 72 may be used to create a subatmospheric pressure in thecondenser 60 and the tower 6 if desired.

Under certain operating conditions it may be desirable to use aplurality of ball mill `cham-- bers in series in order to effect thedesired cracking of the oil or to give additional cracking capacity.

In order to prevent corrosion and carbonization of the steel of whichthe apparatus (including the balls 30) is constructed, it may be tin,chromiumor aluminum. i e

In the I The various parts of the lapparatus which would be exposedtoradiation losses'are preferably covered with insulation., Besideshaving a coat of insulation on the chamber 18, it is also preferably setin aV housing constructedor lined with insulating Vmaterials so as`tocut down the heat loss.v These various features are not shown in thedrawing inorderto avoid complicating thefsa'me.

It is understood thatthe metal vbal1s30 may be substitutedbyelementshaving other shapes or rods, etc., without departing from the spirit andscope of the invention, the broad aspect being theemployment of suchloose elements as will free the carbon from themselves and the Walls ofthe chamber'and/orjpulverize'the same therein. e Y

Various other features of..constructionY and operation may be resortedto Without departing yfrom the spirit and scope of the presentinvention, such for example as not returning any part of the residuurnfrom the cracking chamber to the heater, using a by-pass around thechainber 18 to the chamber 34v forza portion of the oil from the heater14 or constructing the reaction chamber 18 with other than acircularcross section. lIt may be made polygonal for example. Y.

`Having thus described the preferred form of the invention, what isclaimed as new is:

l. An apparatus for distilling Yoils comprising an unheated rotatablecracking still, a plurality of metal balls in saidstill, aicoolingchamber, means for passing vapors from ,said still Vto said chamber,means for spraying oil into said chainber to cool said vapors, afractionating tower, means for conducting vapors fromsaid chamber intosaid tower, means to rotate said still and means for heating oil fromsaid chamber and for conducting the heated oil into said still.

Aso

2. The process of cracking oil ina heating coil and in a rotatableexternally unheated reaction drum containing freely-moving; `looseabrading elements, which comprises passing oil through the heating Vcoiland directly into the drum, heating the oil to a ycracking temperaturein said coil, rotating said drum to causethe loosening and grinding bysaid elements ofthe residue produced from cracking said oi1,. Vandwithdrawing from said drum the products Vof the cracking reactionwhilethe drum is4 in rotation. Y. .Y

3. The process of` cracking hydrocarbon loils for the production Aof.gasoline-like products, which comprises passing the oil in-a connedstream under superatmospheric pressure through carbon or coke and toremove any coke deposited Von the Walls thereof, withdrawing oil residuefrom said chamber, conducting oil vapors from said chamber into adephlegmating zone and subjecting the vaporized oil constituents to dephlegmating conditions in said kdephlegmating zone, to separate thegasoline-like materials from higher boiling vapors. Y

4.In the process of cracking mineral oils for the production of`gasoline-like products therefrom, in which a body of oil is maintainedunder cracking conditions of temperature and pressure in an externallyunheated rotatable cracking chamber containing a plurality of loose'metallic abrading elements', the improvement which comprises rotatingsaid chamber, causingsubstan-V tial vaporizationof the oil Vinsaid-chamber, conl ducting vapors from said chamber to a'fractionalcondensing Zone wherein a reflux condensate is produced suitable forcracking, heating reiiux condensate from said zone to crackingtemperature, and passing the products resultingl from the Y heating ofsaid reflux condensate while at a high temperature into said rotatablevcracking chamber. 1

5. In the process of cracking 'mineral oils for the production of lowerboiling point products therefrom in `which a mixture of oil and gas ispassed through a heating Zone in which the mix- `ture is heated to thecracking temperature of the l oil and the resulting products from saidheating introduced into a body of oil maintained at a crackingtemperature in an externally unheated y rotatable cracking stillcontaining a plurality of relatively heavy abrading elements, theimprovement which comprises rotating said still to prevent the formationof cokeon the still walls by abrading elements of greater specic gravitythan the oil to be distilled, which comprises subjecting a body of oilin said chamber toa distilling temperature sufficient to vaporizesubstantial portions of the oil, passing thevapors evolved from the oilin said chamber into a cooling chamber, distributing oil to be distilledintofthe'vapors insaid coolrelatively cool fluid.

ing chamber whereby said oil is topped and said. vapors cooled, passingthe resulting cooled vapors into a rectifying zone and passing thetopped oil through a heating zone and into the body of oil undergoingdistillation in said vaporizing chamber.

'7. The process ofcracking oil in a heating coil and in a rotatableexternally unheated reaction drum containing freely-moving looseabrading elements which comprise passing voil through the lheating coiland Idirectly therefrom into the drum,l r

heating the oil to -a cracking temperature in the said coil, rotatingsaid drumto cause the loosen-A ing and grinding of said elements of theresidue produced in cracking said oil, withdrawing the vapors producedin the cracking operation from K I said drum during the rotationvthereof and conducting them into a fractionatingzone, and immediatelyAcoolingthe vapors withdrawn fromy said drum to a temperature below thecracking temperature by contacting them with a cooling Y fluid prior totheir fractionation in said fractionating zone. Y

8. The process defined by claim 3v in which the vapors conducted fromsaid chamberr into the dephlegmating Zone are brought into intimatecontact with a relatively cooler oil whereby the temperature of thevapors is reduced below the cracking point thereof. p

9. The process defined' by claim 4 in which the vapors conducted vfromsaid chamberto said fractional condensing zone'are cooled to atemperature below that at which further cracking takes .placebycontacting therewith a relatively cool fluid. s

, v10..Th'e process defined by claim 2 in which. products ofthe crackingreaction withdrawn `from said drum are immediately cooled belowv thecrackingv temperature `by lmixing them with a WILBUR G. LAIRD.

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